

Class_ T ^fe345 ' 

Book_ .V\ fS4 _ 

Copyright N°_ 


COPYRIGHT DEPOSIT. 

































TELEPHONE TROUBLES 


THEIR LOCATION AND REMEDY. 


BY E. M. WEV. 

0 



NEW YORK: 

MCGRAW PUBLISHING COMPANY„ 
1907. 






LIBRARY of CONGRESS 
Two Cooies Received 
JUN 6 190 r 


Copyright Entry 
C 

' VY« ^0. 



Copyrighted, 1907, 
by the 

McGraw Publishing Company, 
New York. 







NOTE. 

In putting this little book before the telephone 
workers I do so with the idea of helping the beginner 
and furnishing a guide for the experienced man. It 
is composed of information gained by 15 years’ 
practical experience. E. M. W 

April, 1907. 






CONTENTS. 

CHAPTER. PAGE. 

I. Direct Line. 1 

II. Two Party Line. 14 

III. Four Party Set. 17 

IV. How to Test For and Clear Troubles in 

Private Branch Exchange Switchboards 25 

Inspection. 40 


\ 







TELEPHONE TROUBLES. 


CHAPTER I. 

DIRECT LINE * 

Bell Doesn’t Ring at all. 

May be caused by any of following: 

1st. Condenser open. 

2d. Ringer open. 

3d. Hook contacts crossed. 

4th. Desk stand cords or induction coil crossed. 

5th. Extention bell open. 

6th. Ringer short-circuited. 

7th. Trouble at central office. 

1st. When condenser is open you will get weak 
hook clicks and side tones and hearing very weak. 
Prove by short-circuiting the condenser at the lugs 
with a test cord, which should make the ring of the 
bell and hearing O. K. 

(While the condenser ' is short-circuited you will 
get only one hook click.) 

*Where reference is made to “hook clicks” in these in¬ 
structions, the instrument is understood to be a desk stand, 
wall sets are so connected as to give only one hook click on 
raising or lowering the hook. 

When reference is made to the red, white or green strand 
of the desk stand cord, it is understood that the red goes to 


1 




2 


TELEPHONE TROUBLES. 


2d. Only one hook click, the side tones normal, 
and the failure of the ringer armature to move when 
you. raise or lower the hook, indicates that the 
ringer is open. 

Prove by replacing the receiver on the hook and 
then bridge across the condenser lugs with your 
head receiver; if you do not get a good click every 
time you make contact, the ringer is open. 

Or you can make the following test; open the 
strap at the top of the bell, then short-circuit the 
condenser lugs with a test cord; then connect one 
side of your head receiver to one of the line binding 
posts, and feel with the other side on the terminals 
of the ringer; if you get battery on one terminal 
and not on the other the ringer is certainly open. 

3d. Only one hook click, side tones normal, 
failure of the ringer armature to move when you 
raise and lower the hook, and the receiver in circuit 
while the hook is down, indicates that the hook 
contacts are crossed together. When this is the 
case, the bell will ring poorly or not at all, and the 
ring can be heard in the receiver when the hook is 
down. Open the receiver circuit at one of the 
receiver binding posts, this should allow the bell to 
ring all right. 

4th. Red and white strands of desk stand cord 

the hook, the white to the receiver and the green to the 
transmitter; using the standard Western Electric cord. 

When reference is made to L 1 L 2 orG 1 you will find them 
on diagram No. 1 or No. 2. When reference is made to “A” 
or “B” you will find them on diagram No. 3. 



DIRECT LINE. 


3 


or primary and secondary of induction coil crossed 
together will generally cut down hearing; it may 
or may not cause only one hook click, and may or 
may not put battery through the receiver, and may 
wholly or only partly prevent the bell from ringing. 
Disconnect the strap on top of the bell and test 
with your head receiver from the G post to the L 2 
post; if you get battery there is a cross; disconnect 
the red and white strands of the desk stand cord, 
this will show whether the trouble is in the desk 
stand cord or in the bell. If it is in the bell, dis¬ 
connect No. 2 and No. 4 terminals of the induction 
coil, and test again, to prove certainly that the 
trouble is in the coil itself and not in the wiring. 

5th. If there is an auxiliary bell, and it is open, 
the set will test as though it had an open ringer. 
Test by short-circuiting the L 2 and G posts, which 
cuts out the auxiliary bell and makes it a straight 
set for the time being. 

6th. If the ringer is short-circuited you will get 
battery through the receiver, which .can be detected 
by listening while you short-circuit the receiver 
binding posts with your screw driver blade. To 
prove, disconnect the bridge from the top of the 
bell, and connect the two line wires to the L 2 and 
G posts instead of the L 2 and posts; short-circuit 
the condenser lugs with a test cord, and then bridge 
your head receiver across the ringer terminals; if 
the ringer is all right you will get a heavy click, if it 
is completely short-circuited you will get no click 
at all, if it is partially short-circuited you will get a 
partial click. 


4 


TELEPHONE TROUBLES. 


Bell Rings Weakly. 

May be caused by: 

Poor adjustment of armature or gongs. 

Pivot screws too loose or too tight. 

Clapper rubbing on guard. 

Wiring interfering with the clapper stem. 

“ Whiskers ” on the magnet heads. 

Magnet heads sticky or gummy. 

Desk stand cord, induction coil, or hook contacts 
crossed. 

One or both coils of the ringer partially short- 
circuited. 

Polarizing magnet weak. 

Carbons in protector dirty and generator current 
jumping across them. 

Trouble at the central office. 

Bridge on the Line, Steady Light at Central Office. 

Prove whether the trouble is in the instrument 
or not by disconnecting both sides of the line at the 
top of the bell and going in with your head receiver. 
If you get central the trouble is in the instrument and 
the same will be found either in the wiring, desk stand 
cords, or the hook. If opening the strap (see diagram 
No. 1) does clear the trouble, the leak is across 
through the ringer, and must be due to: 

1. Receiver contact of hook not breaking. If 
this is the case, opening the receiver circuit at one 
of the receiver binding posts will clear the trouble 
temporarily. 


DIRECT LINE. 


5 


2. White and green strands of the desk stand 
cord crossed together. If this is the trouble, dis¬ 
connecting the cords from the bell will clear it. 



3. The condenser must be short-circuited if the 
trouble is not in the hook or cords; if the condenser 
is completely short-circuited, there will be but one 






























TELEPHONE TROUBLES. 


hook click, but often there is enough resistance in a 
condenser short-circuit to give both hook clicks. To 
make sure that the trouble is in the condensfer 
itself, and not in the wiring, disconnect one terminal 
of the condenser and go in series with your head 
receiver. 

Instrument Entirely Dead, Nothing can be Heard 
in the Receiver. 

See first that you have battery at the top of the 
bell. 

The trouble may be due to: 

1. Receiver circuit open. 

2. Receiver short-circuited. 

1. If there is an open in the receiver circuit, it 
may be in either the receiver itself, the receiver cord, 
the white strand of the desk stand cord, the receiver 
contact of the hook, or the secondary; bridge your 
head receiver successively around these parts, when 
you bridge around the open you will get the side 
tones in the head receiver. To prove whether a 
receiver is short-circuited or not, connect your head 
receiver in series with it; if the head receiver responds 
while another receiver in series with it does not, the 
other one cannot be open, and therefore, must be 
short-circuited. 

Transmitter out of Circuit, but Hearing not Entirely 
Cut Out. 

May be caused by: 

1. Open in green strand of desk stand cord, 
transmitter or transmitter wiring. 


DIRECT LINE. 


2. Transmitter short-circuited. 

3. Red and white strands of desk stand cord 
crossed together. 

1. No hook clicks, transmitter entirely dead, but 
can hear induction on the line, and can hear the 
effect of short-circuiting the line at the top of the 
bell, indicates an open. Locate by connecting one 
terminal of your head receiver to the L t post, and 
feeling with the other terminal successively on the 
several points of the transmitter circuit from the 
L a post to the hook; as soon as you pass the open 
you will cease to get battery through the head 
receiver. 

2. Strong hook clicks, transmitter entirely or 
nearly dead, but can hear induction on the line and 
the effect of short-circaiting the line at the top of 
the bell, indicates transmitter short-circuited. Open 
at the transmitter and put your head receiver in 
series to see whether the trouble is a short-circuit 
inside of the transmitter head, or a cross of the trans¬ 
mitter cord or the green strand of the desk stand 
cord with the frame of the desk stand. 

3. Two hook clicks, but the transmitter dead 
and cannot hear induction on the line, and cannot 
hear the effect of short-circuiting the line at the top 
of the bell, andbell rings poorly ornot at all, indicates 
red and white strands of the desk stand cord crossed 
together which short circuits the receiver while the 
hook is up. Disconnect the strap at the top of the 
bell, and test as previously directed from the G post 
to the L 2 post; if you get battery the cord is crossed. 


8 


TELEPHONE TROUBLES. 


Transmission Poor. 

May be due to: 

1. Transmitter packed or otherwise bad. 

2. Red strand of desk stand cord, primary, or 
hook contact open (in which case the hearing will 
also be poor). 

3. Primary or secondary reversed. 

4. Primary and secondary crossed together( this 
will also affect the hearing). 

5. High resistance in the line or instrument. 

1. When a transmitter is believed to be packed, 
call the wire chief, being very careful not to shake 
it up or jar it, and get him to note the way it transmits; 
then shake it up thoroughly, and see what the effect is 
on transmission. When a transmitter is suspected 
of packing but you fail to catch it in the act, you can 
sometimes pack it by blowing gently into the mouth 
piece for a minute or so; but in making this test be 
careful not to condemn a good instrument, as almost 
any transmitter is liable to a certain amount of 
packing, and will come up stronger immediately 
after having been shaken up. 

When a transmitter is suspected of being otherwise 
defective a sure test can be made by temporarily 
swapping faces with some other instrument that 
is all right. 

2. Only one hook click and weak side tones 
indicate primary or red cord open. Connect one 
terminal of your head receiver to the L 2 post and 
test with the other successively on the L t post, No. 
1 and No. 2 terminals of the induction coil, red cord 


DIRECT LINE. 


9 


post in desk stand, hook spring, and hook; as soon 
as you pass the open you will not get battery. 

3. Examine 1 and 2, and 3 and 4 of the coil to 
see that they are not reversed, that is, see that the 
numbers of the coil terminals correspond with the 
numbers of the lugs that they connect to. If the 
coil is reversed internally, so that the numbers 
correspond but nevertheless one of the windings is 
wrong, it can only be detected by the man at the 
other end. Call up the wire chief or go to another 
instrument yourself and listen to the transmission 
from the suspected instrument; if the coihis reversed 
the transmission will be muffled. Prove by reversing 
either the primary or the secondary, which should 
clear the trouble. 

4. Test as previously directed for primary and 
secondary crossed together. 

5. Get the wire chief to test the resistance of 
the line, or test it yourself as follows: Bridge your 
lamp on at the top of the instrument, the lamp will 
bum rather dimly on an ordinary line, very dimly 
if it is a long line, or an extension line from a private 
branch exchange with a high resistance drops and 
retardation coils. (In the latter case the test can 
be made better after the operator has plugged up 
the line.) Next connect your line in series with the 
instrument, take the receiver off the hook, and 
compare the brightness of the lamp while the instru¬ 
ment is in circuit, and while it is cut out by short- 
circuiting the L x and L 2 posts. If there is much 
difference noticed there is a high resistance in the 


10 TELEPHONE TROUBLES. 

instrument. Forty ohms is a fair average for the 
resistance of a central battery instrument, but it 
may be higher or may be lower, it may run below 



30 ohms. About 16 ohms of this is in the primary 
and the rest is in the transmitter. To prove that 
there is no resistance in the soldered connections 



























DIRECT LINE. 


11 


or hook contact, short-circuit both the primary 
and the transmitter; this should cut out all of the 
resistance and completely short-circuit the instru¬ 
ment, so that you will get no battery from L t to L 2 
posts when the hook is up. 

The resistance of a 24 volt test lamp is somewhere 
about 400 ohms cold and 240 ohms hot. 

Hearing Poor. 

May be due to: 

1. Receiver bad. 

2. Receiver cord or white strand of desk stand 
cord bad. 

3. Condenser open. 

4. Primary and secondary crossed together. 

5. Primary short-circuited. 

6. Secondary short-circuited. 

7. High resistance in secondary circuit. 

There will be two hook clicks with any of the 
above troubles, but one of the clicks may be cut 
down more or less. 

1. Examine the receiver for dented diaphragms, 
“ whiskers ” on the magnets, magnets too close to 
diaphragm, or magnets weak; test by putting your 
head receiver in series with it and comparing the 
hearing. 

2. To test the receiver cord and the white strand 
of the desk stand cord, put battery through them 
and listen in the receiver for a cut out or scratchy 
sound while you shake them. Short-circuiting the 
condenser with a test cord puts battery through the 
receiver and its cords when the hook is up. 


12 


TELEPHONE TROUBLES. 


3. If the condenser is open the ringer usually 
will not ring, but sometimes you can ring through 
a condenser that you cannot hear through at all. 
Test by short-circuiting it with a test cord. 

4. Primary and secondary crossed together will 
usually short-circuit the ringer and prevent your 
getting a ring. Test as previously directed. 

5. If the primary is short-circuited bridge your 
head receiver around it; you will get no click when 
the hook comes up, and no side tones. If the primary 
is all right you will get both clicks and side tones in 
your head receiver. 

6. A short-circuited secondary can be tested 
by exactly the same method as is given above for 
testing the primary. 

The above tests work very well if the primary or 
secondary is completely or nearly short-circuited, 
but if the short circuit is only partial it is very hard 
to detect. If you are .in doubt, change the bell 
temporarily for another bell that is all right or change 
the induction coil, and compare results. 

7. To test for a high resistance in the secondary 
circuit, put battery through it by short-circuiting 
the condenser with a test cord while the hook up, 
then listen in the receiver while you short-circuit 
successively the receiver hook contact, the two 
sides of the receiver cord, the white strand of the 
desk stand cord, the wiring from receiver cord to 
secondary, from secondary to condenser, and from 
condenser to L 2 , and the secondary itself; when 
you short circuit out any part of the circuit that 


DIRECT LINE. 


13 


contains resistance, such as the secondary itself, more 
battery will flow through the receiver, giving you a 
click. 

An instrument in which the ringer is not connected, 
will, of course, give but one hook click. 

Reversals in the connecting up of desk stand 
cords may cause only one hook click or poor hook 
clicks, poor transmission, poor hearing, transmitter 
nearly dead, etc., according to the combination in 
which the three strands of the cord are connected. 

If the ground side of the line is open outside the 
set may be put in temporary service by working to a 
local ground. 

If the induction coil is bad, temporary service can 
be given, i'f necessary, by putting the transmitter 
and receiver in series, and properly poling the receiver. 


CHAPTER II. 


TWO PARTY LINE. 

No. 1 Set. 

(The battery side of the line goes to the L 2 post.) 

Gives two hook clicks, and can be tested in very 
much the same way as a straight set, but the following 
points should be remembered: on sets that ring to 
ground an open ground will, like ringer open, cause 
the bell not to ring and only one hook click. 

Resistance in the ground may cause poor ring. 

Reversal of the three wires on top of the bell may 
cause only one hook click, bell not to ring, and 
transmitter nearly dead. 

Transmitter very poor may be caused by the 
ground side of the line being open outside. (You 
can still call the operator and talk, with difficulty 
through the ringer and ground.) 

No. 2 Set. 

Gives but one hook click, but otherwise can be 
tested in very much the same way as a straight set. 
Remember the following points: 

On sets that ring to ground: 

Ground open will prevent bell from ringing. 

Resistance in the ground may cause poor ringing. 

A ground on the ground side of the line may 
14 


TWO PARTY LINE. 


15 


cause the bell to ring poorly or not at all by takirg 
the generator current oh to ground before it reaches 
the instrument. 

Condenser short-circuited will not only put a 
ground on the ground side of the line through the 
ringer, but on exchanges which use pulsating cur¬ 
rent for ringing will also cause bell to ring poorly 
or not at all. 

Reversals of the three wires on top of the bell 
may cause two hook clicks, bell not to rmg, and 
transmitter nearly dead. 

On two-party sets, to find reversals of the wires 
at the top of the bell, trace out the wire to the pro¬ 
tector, or else find out with your head receiver 
which one of the three wires is alive to both of the 
others, or to an independent ground. This one is 
the battery side of the line. 

To test for reversal of the ground wire with the 
ground side of the line, bridge your head receiver 
from an independent ground to the two doubtful 
wires successively. You will get induction on the 
line wire, and none on the ground wire. Or, bridge 
your receiver from the battery side of the line to the 
other two wires successively; the one that gives the 
most induction in this case is the ground wire. Or 
again, test by bridging your lamp from the battery 
side of the line to the other two wires successively. 
If the ground is good, bridging to it will give a 
brighter lamp than bridging to the ground side of 
the line; only a little brighter if the line is short, 
much brighter if the line is long. 


16 


TELEPHONE TROUBLES . 


The above is also the way to test for a poor ground. 
The resistance of the ground return back to the cen¬ 
tral office should be less than the return through 
the cable, therefore the lamp should bum brighter 
on the ground wire than on the ground side of the 
line; very little brighter if the line is short, much 
brighter if the line is long. 

An extension bell open will prevent the main 
bell from ringing, just as in a straight set. Test 
by running a temporary ground, or by short-circuiting 
out the extension bell. 

If you are in doubt when testing a two party set, 
disconnect the ground wire and strap the bell, making 
it a straight set temporarily, and then test the 
ringing, transmission, and hearing. A straight set 
will respond to all rings, direct, two-party, and four- 
party. 

If on a two-party set the ground side of the line 
is open outside, temporary service may be given, 
if necessary, by working to the local ground. 

If the ground is open, temporary service can be 
given, if necessary, by converting to a straight set; 
but in this case the bells will respond to both calls. 

If second instrument is properly poled and bell 
rings when first station is being called, the trouble 
is probably due to party at first station taking his 
receiver off the hook before the operator has stopped 
ringing, and vice versa. 


CHAPTER III. 


FOUR PARTY SET. 

(Diagram No. 3.) 

Tests of the transmitting and hearing circuits 
can be made in very much the same manner as in 
a straight set. On account of the relay coil being 
bridged between No. 2 and No. 3 terminals of the 
induction coil, a four-party desk set, if in perfect 
order, will give two hook clicks, no matter how it is 
poled. 

To make a perfectly sure test for primary and 
secondary crossed together, it is necessary to discon¬ 
nect one terminal of the relay winding; then with 
the receiver on the hook, test from the L 2 post to 
the secondary with your head receiver; if you get 
current there is a cross. 

Reversals of the three wires at the top of the instru¬ 
ment may cause a variety of troubles, just as in the 
two-party sets. 

Ringing Circuit. 

Relay: Failure of the relay to come up when the 
operator rings may be caused by: 

Condenser open. 

Relay short-circuited or open. 

Hook contacts, or red and white strands of defck 
17 


18 


TELEPHONE TROUBLES. 


stand cord, or primary and secondary of induction 
coil crossed together. 

Primary open. 

Trouble at central office. 

Test just as though it was a straight set except 
when testing for relay short circuited, or for a cross 
between primary and secondary, (in which case 
you must open one terminal of the relay winding, as 
previously directed); and except when testing for 
relay open, which you can do by bridging your head 
receiver from L 2 post to No. 2 and No. 3 terminals 
of the induction coil successively; you should get 
strong battery on No. 2 terminal, if the relay is 
all right and a strong condenser discharge when you 
make contact, but a weak battery click when you 
break contact, on No. 3 terminal. 

A ground on the ground side of the line may also 
prevent the relay from operating, by carrying the 
generator current off to ground before it reaches 
the instrument. 

If the relay is held up, usually the lamp is kept 
burning at the central office also, and this means 
that current is flowing from the central office over 
the battery side of the line, passing through the 
relay winding, and returning to the central office 
over the ground side of the line, or through the 
ground wire and ground. This condition may be due 
to: 1st. Winding of relay crossed with frame. Test 
by disconnecting the “ A ” or “ B ” terminals of 
the ringer from “ L 2 ” which should release the relay. 
2d. As in the case of current through the ringer of a 


FOUR PARTY SET. 


19 


straight set, the trouble may be caused by receiver 
contact of hook not breaking, white and green 

Line 



strands of desk stand cord crossed together, condenser 
short-circuited. Test as though it was a straight set. 


































20 


TELEPHONE TROUBLES. 


If the relay vibrates continuosly the winding is 
probably crossed with the frame. To find out 
whether this is the case, disconnect the ground wire, 
which should stop the vibrating. 

If the relay “ jumps ” while the operator is ringing, 
instead of pulling up and staying up as long as the 
ringing current continues, the relay may be weak, 
due to a part of the winding being short-circuited 
out, or to some other cause; or there may be too 
many bells and relays on the line, so that, owing to 
the resistance of the line, not enough generator 
current will flow over it to divide up and give each 
bell and relay a proper amount of current; or there 
may be a slight ground on the line, which carries off 
a part of the ringing current. 

To prove that a relay is all right: 

1. Short-circuit the condenser; this should hold 
up the relay, by putting battery current through it. 

2. Prove that the spring contact is not crossed 
with the frame as follows: Disconnect “ A ” and 
“ B ”, then connect the frame of the relay to battery 
with a test cord, and bridge from the spring contact 
to ground with your head receiver; if you get no 
current, there is no cross. 

3. Prove that the winding is not crossed with 
the frame as follows: Disconnect “ A ” and “ B ” 
and then test with your head receiver from the frame 
to the L 2 posts; if you get no battery there is no cross. 

Ringer: If the relay comes up, but the bell does 
not ring, the trouble may be due to: 

Ringer poled wrong. 


FOUR PARTY SET. 


21 


Bias spring too tight or too loose. 

Ringer open. 

Ground open. 

Ringer short-circuited. 

Bridging your head receiver across the ringer 
while the operator is ringing will show whether or 
not you are getting generator current on the term¬ 
inals of the ringer winding; going in series at the 
“ A ” and “ B ” terminal will show whether or not 
you are getting current through the ringer. 

To prove whether a ringer is open or not, connect 
“ A ” to battery, hold the relay closed, and then 
test from “ B ” to ground'with your head receiver; 
if you get no current the circuit is open; prove that 
the open is in the ringer itself by testing direct from 
the two terminals of the winding successively. 

The ground can be tested in the same manner as on 
a two-party set. 

To prove that the ringer is short-circuited, connect 
“ A ” and “ B ” across the line, close the relay contact, 
and bridge across the terminals of the ringer winding 
with your head receiver; if you get no click the 
ringer must be short circuited; check this test by 
putting your head receiver in series with the* ringer, 
while it is connected across the line, and closing 
the relay contact; this should give you a strong 
click if the ringer is short-circuited. 

Bell ringing weak may be due to: 

Poor adjustment of armature. 

Poor adjustment of bias spring. 

Pivot screw too loose or too tight. 


22 TELEPHONE TROUBLES. 

Clapper rubbing on guard. 

Wiring interfering with clapper stem. 

“ Whiskers ” on magnet head. 

Magnet head sticky* or gummy. 

Polarizing magnet weak. 

One or both coils of ringer partially short-circuited. 

Too many bells and relays on the line. 

Ground on one side of line which takes part, of the 
generator current off to ground before it reaches 
the instrument. 

Trouble at central office. 

Earth currents. 

To test for earth currents bridge your head re¬ 
ceiver from the ground side of the line to the ground; 
you should get no current; if you do get current you 
will probably find that it varies continually, being 
due to trolley cars; report the matter to the chief 
inspector. In making this test be sure that the line 
is not in use; if the receiver is off the hook at any 
station on the line you will get a false test. 

Earth currents very often cause bell troubles on 
suburban stations, particularly those that lie near 
to trolley lines; but in the city, earth currents are 
seldom noticeable. 

False rings may be caused by: 

Very strong earth currents. 

One coil of ringer short-circuited. 

If a biased ringer has one coil short-circuited, 
then when it is poled for either 1st or 2nd stations 
it will respond to both rings; and likewise when poled 
for 3d or 4th stations it will ring with either current. 


FOUR PARTY SET. 


23 


In the bell diagram No. 3 you will see that “ B 
connects to the spring contact of the relay, the frame 
of the relay connects to the biased side of the ringer, 
and the unbiased side of the ringer connects to A. 

In the older bells, “ B ” connects direct to the 
biased side of the ringer; the unbiased side of the 
ringer connects to the spring contact of the relay, and 
the frame of the relay connects to “A.” 

Therefore, in connecting an extension bell to a 
set that has no extension bell binding posts, connect 
one side of the wire to the frame screw of the relay, 
under the bottom of the set, and the other side to 
the post at the top of the bell that “ A ” connects 
with. Or solder one of the extension bell wires to 
the spring contact of the relay, and connect the 
other to the post at the top of the bell that B con¬ 
nects with. In every case the auxiliary bell must be 
connected across the terminals of the ringer without 
being bridged around the break of the relay. Pole 
the extension bell by reversing the wires either at 
the be’ll or at the set. 

Ringer Adjustments: In adjusting a biased ringer 
find out the two points where the bell ceases to ring 
on account of ther bias spring being too tight and 
too loose, and adjust the spring half way between these 
points. To locate them, slack off the bias spring 
until it has no tension at all, and then get the oper¬ 
ator to ring while you tighten up the spring, and 
note the point at which the bell commences to ring; 
continue to tighten the spring until the bell ceases to 
ring; by making the adjustment half-way between 


24 


TELEPHONE TROUBLES. 


these two limits, you will have a margin both ways, 
so that if the generator rises a little above or falls 
a little below its proper voltage, the bell will still 
ring. 

The little set screw in the yoke at one end of the 
armature should be adjusted so as to hold the opposite 
or bias spring end of the armature a little away from 
the head of the magnet core; 0.02 of an inch, which 
is a little less than the diameter of a No. 22 cross¬ 
connecting wire, “ In every test use a little judgment.” 


CHAPTER IV. 


HOW TO TEST FOR AND CLEAR TROUBLES IN 
PRIVATE BRANCH EXCHANGE SWITCHBOARDS. 

Station can’t call: When a station can’t call, 
the trouble may be due to the line being open, or 
too much resistance in the line; or to the signal 
being open, or short-circuited, or stuck. 

Short-circuit the line in the back of the 
switchboard or at correcting frame; if the signal 
does not operate plug up the jack with a plug 
and see if the cord signal will operate; if it will not 
the open is between the frame and the springs 
of the jacks if the cord signal will operate, the trouble 
is back of the jack springs, and may be an open, or 
it may be that the drop is short-circuited or stuck. 
Test with a receiver or lamp, if you get good battery 
on the locknuts but can’t throw the drop, it must 
be short-circuited or stuck; if you get no battery 
there is an open; short-circuit the inner contacts 
of the jack, and if this brings up the signal the open 
is in the jack; take the jack- out and repair it. • If 
short-circuiting the inner contacts will not operate 
the signal, the same may be open; test from the 
ground strap of the jack direct to the signal terminals; 
if the signal tests all right the wire leading from one 
side of the signal to one inner contact of the jack 

25 


26 


TELEPHONE TROUBLES. 


must be open; prove by short circuiting same out 
with a test cord. 

If there is battery on the jack but the signal won’t 
come up, push gently against the back of the armature 
of the signal with a tooth pick until it starts to raise; 
you can teel by the feeling if it is at all stuck. 

Another good way to tell whether the signal sticks 
is to go to the station and hold the receiver to your 
ear and then allow the hook to raise. When the 
signal flies up it can be heard in the receiver as a 
sort of “ tremble.” This “ tremble ” should take 
place the instant the hook comes up; if it is delayed, 
the signal must be sticking. 

This test can also be made from the frame with 
a head receiver. 

To test whether the signal is short-circuited, see 
how brightly your lamp bums when connected at 
the frame and then compare with other signals 
which are all right; a signal which is wholly or partly 
short-circuited will have less resistance than the 
others, and the lamp will bum brighter. 

If the signal comes up from the frame but will 
not come up from the instmment, the line may have 
too much resistance and the signal will have to be 
adjusted so as to be more sensitive. 

If a station on a long line has trouble calling at 
times, there may be a poor connection in the circuit 
which varies; or it may be that the signal fails to 
work only when the board is busy, due to the drop 
in voltage on the battery feed when much current 
is being drawn from it; the signal will have to be 
adjusted more delicately or the battery feed increased. 


PRIVATE BRANCH TESTS. 


27 


Station Signal Stays up: The line must be either 
crossed, or grounded on the battery side. Plug into 
the jack with a detached plug and cord, and then 



test successively on the ring and tip of the detached 
cord with a receiver or lamp that is connected to 
battery. This will show if there is a ground on 












































































28 


TELEPHONE TROUBLES. 


either side of the line. If both sides test clear of 
grounds, there must be a cross; to prove this, ground 
the tip side by holding the tip of the detached cord 
on the tip of any other plug; if there is a cross the 
ring side will then test grounded. To locate the 
trouble, open the line successively at the frame 
cable box instrument, etc., and note the effect on 
the signal. 

In testing with a receiver for grounds or crosses 
on lines, you should be guided by the click when you 
break contact; otherwise, you are likely to be de¬ 
ceived by the electrostatic capacity of the line and 
condenser in the instrument. In such tests you 
may get a strong click when you make contact, 
particularly if the line runs through a cable, and 
you may also get plenty of induction on the line; 
but if you do not get a click when you break contact, 
there is no current flowing through your receiver, 
and therefore the line is clear. 

If plugging into the jack does not restore the 
signal, the trouble must be a cross in the jack, or 
in the signal itself. Examine the jack lugs, and 
also the inner end of the signal winding, which may 
be in contact with the iron mounting strip. If 
the trouble is not here, disconnect the wire going 
to the jack from the signal; this will show whether 
the trouble is in the signal itself. 

If the sleeve of a station jack is grounded, the 
cord circuit relay will operate when you plug into 
the jack, and cut the battery off of that pair of cords. 
Touching the tip of a plug to the sleeve of a station 


PRIVATE BRANCH TESTS. 


29 


jack with the listening key thrown will show if the 
sleeve is grounded by giving a click in the operators 
receiver, the same as touching the sleeve of a trunk 
jack will do. The ground may be due to the sleeve 
being crossed with the sleeve of a trunk jack, or 
crossed with the sleeve of a station jack that is con¬ 
nected to a trunk jack; or it may be between the 
sleeve and the inner contact of the jack on the 
ground side. 

Battery Feed and Trunks: The battery feed 
and trunks must always be poled properly. To 
test the poling of the feed, run a temporary ground 
and touch it to the ring of the back plug. If this 
does not bring up the cord signal the feed is poled 
wrong, and the feed and ground will have to be 
reversed. 

To test the poling of a trunk, plug into the trunk- 
jack with the front plug of any pair, say No. 1 pair; 
then touch the tip of any other plug to the ring of 
the back plug of No. 1 pair; if this does not bring up 
the cord signal on No. 1 pair the trunk is poled 
wrong. 

One of the troubles caused by the wrong poling 
of a trunk is that if the operator plugs in to answer 
the trunk while she has another listening key thrown, 
her transmitter goes dead. 

If operator at the central office can’t throw a 
trunk drop at a private branch switchboard the 
same may be open, or the condenser may be open. 
Bridge a receiver across the drop; if yon can get a 
good ring in the receiver the condenser is all right 


so 


TELEPHONE TROUBLES. 


and the drop is probably open. If you can’t get a 
ring across the drop, short-circuit the condenser; 
if this puts battery through the drop and brings it 
up, the condenser must be open. 

If a cord circuit relay fails to operate on any 
trunk, the ground strap may be broken off of the 
jack. Plug up the jack, then touch the butt of the 
plug with the tip of a plug of any other pair; if this 
operates the relay, it shows that the sleeve of the 
jack did not operate it, and therefore the sleeve 
connection must be open. 

The sleeve connections are often taken off purposely 
on tie trunks. 

If the operator complains of central cutting her 
off, some of the holding coils may be open. Instruc¬ 
tions are given further ahead for testing them. 

If plugging up a trunk causes the cord circuit 
relay to vibrate the battery feed or ground must 
be open. 

If the line or cord signals fail to come up properly 
the battery feed may be weak; this may be due to a 
poor connection in the feed or ground, or to one 
of the conductors of the feed being open, or to the 
feed being grounded through resistance. Bridge a 
lamp across the feed; it should bum brightly if no 
current is being used on the switchboard. Throw 
a listening key, or bridge a receiver across the feed; 
if this puts the lamp -out, or dims it excessively, the 
feed or ground has a high resistance on it, or some 
of the conductors are open. Disconnect the conduc¬ 
tors one at a time at the table head or protector, 


PRIVATE BRANCH TESTS. 


31 


and see if each one will light your lamp properly. 
If the lamp bums dimly when no current is being 
used on the switchboard, the feed is probably grounded 
through resistance; disconnect it from the switch¬ 
board and test; if it still gives a dim lamp discon¬ 
nect at the protector and test again to prove whether 
trouble is inside or outside. 

The amount that a lamp bridged across a battery 
feed will be dimmed by throwing a listening key or 
bridging on a receiver depends upon the resistance 
of the feed. If the feed is very long the lamp will 
be dimmed very much; if the feed is short or consists 
of several pair, the lamp will be dimmed but slightly. 
Each inspector should become familiar with the be¬ 
havior of the battery feeds on all his important 
boards; he should know how the lamp bums when 
the board is idle, and how much it is dimmed when a 
certain number of connections are up, so that in 
case of trouble he can tell at once by a lamp test 
whether the feed is O.K. or whether it has too much 
resistance, or is partially grounded. 

Troubles Causing Bells to Ring. 

A swinging open or swinging ground on the battery 
feed causes the bells at the stations to ring by charg¬ 
ing and discharging the condensers. 

Generator feed crossed with the battery feed causes 
bells to ring. Examine wiring and generator con¬ 
tacts at ringing keys. 

Where the spring of a station jack does not break 
from, or is crossed with the inner contact, all bells 


32 


TELEPHONE TROUBLES . 


may be rung by ringing on that jack with power 
generator, which is always grounded on one side. 

If the outer contact of a ringing key makes before 
the inner contact breaks, all bells may be rung when 
that key is used, by the generator current passing 
down through one side of the retardation coil to the 
battery feed. 

Cord Circuit. 

Tip and sleeve crossed causes vibrating relay on 
that pair. 

Tip and ring crossed short-circuits the cord. 

Ring and sleeve crossed causes relay to vibrate 
when ring and tip of plug are short-circuited, or when 
the plug is put in a station jack with the station 
receiver off the hook,—sometimes merely throwing 
the listening key on that pair will make the relay 
vibrate. 

Touching ring to tip and tip to ring of the two 
plugs of any pair should give a spark, and the singal 
should also come up when the ring of the plug is 
touched with a tip. If there is trouble, take any 
other plug which is O.K. and test the bad pair; 
if both rings or both tips fail to give a spark, there is 
probably an open at the relay, the retardation coil, 
or the soldered connections on the listening key. If 
. only one cord tests open, and the other one of the 
same pair tests O.K., ring on the bad cord and feel 
for generator current in the plug. If you get cur¬ 
rent, the open must be at the inner contact of the 
ringing key; or, it may be in the cord signal. If you 


PRIVATE BRANCH TESTS. 33 

cannot get generator on the plug, the open is in the 
cord. 

To locate any open that effects both cords, test 
successively on inner contacts and swinging contacts 
of relay, inner and outer lugs of retardation coil, 
and swinging contacts of listening key, you should 
get battery across all of these points. 

If either cord of a pair is short-circuited it short- 
circuits both cords and you will not get proper sparks 
when touching ring to tip and tip to ring but you 
may get small sparks. Also the operators trans¬ 
mitter will be dead on that pair of cords and if you 
test with a receiver or lamp you will get little or no 
battery between the ring and tip of either plug, but 
will get battery of about half the proper strength 
from either the ring or the tip of either plug to either 
the ring or the tip of a plug of any other ^air. 

You can also tell whether a cord circuit is short- 
circuited by bridging your receiver around one half 
of the retardation coil; if there is a short-circuit, 
part of the current that is flowing around through 
the coil will go through your receiver, giving you a 
click. 

To locate the short-circuit, ring on the two cords 
successively, and feel on the plugs for generator. 
If both cords test clear, the trouble must be back 
of where the circuit branches at the listening key; 
disconnect successively at the relay, the retardation 
coil, and the listening key until you locate the trouble. 

In most of the private branch exchange switch¬ 
boards the battery goes first to the inner contacts 


34 


TELEPHONE TROUBLES. 


of the relay, then through the swinging contacts to 
the retardation coil, and from the retardation coil 
to the swinging contacts of the listening key; in 
other boards the battery goes first to the retardation 
coil, then through the relay contacts to the listening 
key. From the listening key it goes to the inner 
contacts of the ringing key, and from the swinging 
contacts of the ringing keys to the cord fasteners. 

If a cord circuit is open at the relay or retardation 
coil, it will still work on a trunk connection, the 
trunk supplying the battery, if the central office is 
common battery system. 

Lamp tests of the retardation coils and cord 
signals can be made by bridging a lamp across the 
bus-bars and then short-circuiting the tip and ring 
of every cord successively. Each one should dim 
the lamp the same amount; if one cord dims it less 
than the others, it shows that there is more resistance 
in that cord circuit—possibly a bad connection, or 
a cord signal with too much resistance. If one 
cord dims it more than the others, there must be 
less resistance in that cord circuit, probably one 
* half of the retardation coil is short-circuited. (This 
test fails where there is a floater battery, or a battery 
feed of very low resistance.) To prove that one 
side of the retardation coil is short-circuited, short- 
circuit one of the plugs of that pair, and then bridge 
a receiver successively around the two sides of the 
coil, no click on one side should mean that that side 
was short-circuited. 

A finer test can be made by bridging the lamp 


PRIVATE BRANCH TESTS . 


35 


across the tip and ring of the cord, and shoft-cir- 
cuiting out the two sides of the coil successively; 
each side should brighten the lamp exactly the same 
amount. If one side brightens it more than the 
other, that side has more resistance than the other. 

Unbalanced coils are usually noisy, especially on 
long lines. An unbalanced coil can usually be de¬ 
tected by simply listening on each pair of cords, 
successively; if the battery feed induction is stronger 
on one pair than on the other, that pair is probably 
unbalanced. 

In most boards the holding coil is bridged across 
the outer contacts of the relay. In other boards 
one end of the coil connects to one swinging contact 
of the relay, and the other end to the opposite outer 
contact. To test the holding coil, plug into a trunk 
jack with the back plug and throw the listening key, 
which will bring up the cord signal, then throw the 
listening key normal. If the signal stays up the 
holding coil is O. K. if it disappears the holding 
coil circuit must be open. The trouble may be 
that the relay contact does not close, or the coil 
itself may be open. 

Test by plugging into a trunk with the back cord 
and then short-circuiting the holding coil; if the 
cord signal comes up the holding coil must be open; 
if it does not come up, leave the short-circuit on the 
coil and bridge out the holding coil contacts of the 
relay. When you bridge out the contact where the 
open is, the signal will come up. 

To test the relay on any cord circuit, touch the 


36 


TELEPHONE TROUBLES. 


tip of any other plug to the sleeve of either plug of 
that pair; if this does not operate the relay the 
sleeve conductor of the cord may be open; if neither 
plug of the pair will operate it, the relay itself may 
be open; test with a receiver or lamp. 

Touching the tip of one plug to the sleeve of the 
other plug of the same pair should make the relay 
vibrate. 

To test a switchboard cord, plug into the cord 
testing jack (every board should have a testing 
jack connected to put battery direct on your head 
receiver) and shake the cord, and turn and shake 
the plug in the jack, while you listen in the operators 
receiver for any cut-off or bad connection. Do not 
have any listening key thrown while you are testing 
switchboard cords; also see that the operator 
receiver is poled so that the current from the cord 
strengthens the magnetism instead of weakening it 
otherwise you will not get a sensitive test. The tips 
and rings of the plugs must be clean, or else they 
will be scratchy. 

Be very careful that none of the plugs are bent or 
‘ ‘ lopsided; ’ ’ such plugs may work all right in some 
jacks and cut-off in others. If turning a plug around 
in a jack causes a cut-off the plug should be con¬ 
demned; sometimes the jack may be at fault, and 
the long spring will have to be given more “ set.” 
After changing switchboard cords, always test the 
new ones for opens, short-circuits and reversals. 

Cross Talk: Solder dropped on the cord fasteners, 
or a cross at the keys, may connect two different cord 
circuits together, and cause cross-talk between them. 


PRIVATE BRANCH TESTS. 


37 


Retardation coils may be crossed with their cases, 
and cause cross talk by the cases being in contact. 
Condensers on trunk drops may make two trunks 
cross talk in the same way. Test by bridging a 
receiver from the case of the suspected coil or con¬ 
denser to battery and to ground successively. There 
will be no click if the case is clear. 

Unbalanced retardation coils, or a weak battery, 
may also cause cross-talk. 

A listening key that does not break contact on 
both sides will cause cross-talk when that pair of 
cords is used; if with all keys normal you get a click 
in the operator’s receiver when you touch the tip 
of any plug to the frame of the operator’s transmitter, 
the operator’s circuit is in contact with some cord 
circuit at the listening key. To find out which key, 
see that all keys are normal and then vibrate the 
relay on each pair of cords successively by touching 
the tip of one plug to the sleeve of the other; when 
you come to the pair where the cross is, the buzz 
will be heard plainly in the operator’s receiver; on 
the others it will be heard very faintly. 

Operator’s Set: To test the receiver cord, put a 
plug in the cord testing jack, this puts battery 
through the receiver, and by shaking the cord any 
fault will show up provided the receiver is poled 
properly. Do not have any listening key thrown 
when making this test. 

To test the transmitter cords, throw up any 
listening key and listen in the operator’* receiver 
while you shake the cords. 


38 


TELEPHONE TROUBLES. 


To locate an open in the operator’s primary circuit, 
throw any listening key, and then bridge a receiver 
successively around the several parts of the circuit, 
that is, the 200 ohm resistance coil, the transmitter, 
(including its cords), and the primary. When you 
bridge around the part that is open, you will get a 
click in the receiver. 

To locate an open in the secondary circuit, short- 
circuit out the condenser so as to get battery through 
the circuit and then bridge around the receiver and 
secondary with a receiver until you have found where 
the open is. 

Buzzer and Buzzer Relay: If a buzzer which 
works off the battery feed fails to operate at times, 
although the buzzer relay comes up, probably it is 
not sensitive enough, and when the board is busy 
the battery feed it not strong enough for it. Adjust 
the buzzer more delicately and test it when the 
board is idle and when it is busy. To make a board 
busy artificially, bridge a head receiver across the 
bus-bars; that is equivalent to several pairs of con¬ 
nections being up. 

If some of the station lines are very long, the 
buzzer relay may fail to come up on them, or come 
up so weakly as not to make good contact. To 
cure this, adjust the relay more delicately. 

If a trunk drop won’t operate the buzzer relay 
when the key is up, the trouble is probably at the 
night bell contact of the drop. If none of the trunk 
drops will operate it, the relay may not be adjusted 
delicately enough, or the 500 ohm resistance coil 


PRIVATE BRANCH TESTS. 


39 


may be open. Bridge around the trunk drop contacts 
with a receiver. If you get no battery the coil 
must be open; prove by bridging the coil out and 
repeating the test. 

A heavy ground on the ground side of any station 
line will prevent the buzzer relay from coming up 
by shunting it out. A light ground will sometimes 
cause trouble on the long lines only. 

A short-circuited condenser or a slight leak across 
any line or lines, may hold up the buzzer relay. 
Test the lines for crosses and grounds, as previously 
instructed. If the buzzer relay comes up at times 
when no signal is up, the trouble may be due to 
some station on a long line trying to call, and the 
signal not sensitive enough to come up. 

General. 

To prove that a board is perfectly clear, disconnect 
the battery feed from the negative bus-bar, and put 
a lamp or - receiver in series. If you get no current 
then all the lines are free from crosses, they are 
free from grounds on the battery side, and the 
other circuits in the board are also clear of crosses. 
(This test can only be made when there are no 
connections up, no listening keys thrown, and no 
stations calling.) To prove that the ground sides 
of all the lines are clear, disconnect both the feed 
and ground wires from the bus-bars, and then test 
through a lamp or receiver from the battery feed 
to the ground bus-bar; if you get no current, the lines 
are all clear on the ground side. 


INSPECTION 


How to Inspect Subscribers Instruments. 

1st.—Ask the subscriber if his instrument works 
properly and repair any defect that he reports. 
Also be sure the instrument is securely fastened to 
the wall or desk. 

2d.—Clean and polish the varnished and nickeled 
parts of the instrument; open the bell and see that 
it is clean and in proper condition inside, and that 
the hook, ringer, and other moving parts work prop¬ 
erly and clean the hook contacts with paper if 
they are dirty or make a scratching noise in the 
receiver. 

3d.—See that all binding post connections are 
tight, test all cords; in testing the receiver cord, put 
battery through it by short-circuiting the condenser; 
change any cords or other parts that are defective 
or unsightly. 

4th.—Clean the receiver outside, remove the cap 
and examine the diaphragm and clean the magnets; 
in cleaning the magnets rub them off with your 
coat sleeve or a clean rag rather than with your 
hands, as the moisture from your hand will cause 
them to rust. 

5th.—Examine the adjustment of the bell and 
test by getting a ring from the operator, at the same 
time test the transmission and hearing. 

40 


INSPECTION. 


41 


Test all extention bells by getting a ring from the 
operator; inspect all other apparatus, such as hand 
generators, switches, local batteries, fans booths 
and signs. It is important that signs should be kept 
in good condition; dirty or unsightly ones should be 
cleaned or ordered changed, and you should be 
particularly careful to see that all signs are securely 
hung. 

6th.—Inspect all wiring, including the leading 
in wires, the inside line wires, the battery wires 
and the ground wires; also the protection, the fuses, 
any extention bells and also see that the ground is 
properly made that it is connected to the proper 
pipes. If a gas pipe has been used see that the 
bridge on the meter has not been disturbed since 
the last inspection. 

7th.—See that the protector contains the proper 
kind of fuses, and if it can be gotten at readily; 
examine the connections and remove the cap from 
over the carbons to see that no one has left the carbons 
out. 

8th.—If a subscriber applies to you to have an 
additional instrument installed, take his name and 
address and turn them in to the manager; if he wants 
his telephone moved or disconnected, or circuit 
number changed, or extention bell or sign installed, 
request him to call up the managers office. 

If he complains of poor operating service, or of 
interference by other subscribers on his line, refer 
him to the manager. 

If he complains of some trouble that is in the 


42 


TELEPHONE TROUBLES. 


outside line or at the central office, report the matter 
to the chief inspector at once. 

9th.—In making recommendations, state briefly 
but plainly just what you want done and give the 
reason why. If the installer has done any work 
at the station since your last inspection, and has 
failed to leave it in proper condition, accompany 
the recommendation that you make with a written 
complaint. 

Making First Inspections of New Installations. 

In inspecting a new installation, or an instrument 
that has been moved or changed since your last 
inspection, or in going over your instruments for 
the first time, the inspection should be made more 
carefully than at other times. 

Ask the subscriber if he has any extention stations, 
extention bells or other apparatus attached to his 
instrument, also look out for them while you are 
making the inspection and tracing out the wiring. 

Open the deskstand and see that all the locknuts 
are tight and soldered connections are perfect. 

Examine and shake all soldered connections in the 
bell. 

Trace out all of the wiring and be sure to see that 
all splices are properly soldered and taped and see 
that no tacks are driven in the splice. 

Make a lamp or receiver test of the protector and 
the instrument ground, to see that they are good 
and have no resistance. 

See that the protector is securely fastened, that 



INSPECTION. 


43 


the connections are all tight, that the fuses and 
carbons are of the proper kind, and that the micas 
have the open side down. 

Test the fuses for loose connections inside, by 
bridging your head receiver across the binding 
post at the instrument end of the protector and 
listening for a cut-off, while you shake and jar the 
fuses. 

Test all switches to see that they make all proper 
connections, oil the hand generators and see that 
the bell clapper works freely. 

See that the specifications have been complied 
with in placing the protector and the instrument, 
in running all the wire, and in every other particular; 
that the desk stand cords are cleated, and protection 
cleats used where needed; that desk sets give two 
hook clicks; that snap switches are of the indicating 
type; that the connections to all binding posts are 
neat and of proper length; that the booth is clean 
and have plugs in all the screw holes; that they have 
no broken glass and have lineoleum on the floor, 
and that the doors and latches all work freely. 

See that the protector is placed so as not to be in 
the way of curtains; that no damage has been done 
to the subscribers property; that all apparatus has 
been installed so that it will not be in his way, and 
will not be exposed to disfigurement, damage, 
trouble from dampness or rain, etc., that wire is 
run where it will be safe from injury, dampness and 
wear; in short, see that the installation is done 
according to specifications in every respect. 


44 


TELEPHONE TROUBLES. 


See that the cut-in (the wires from the pole to the 
house) are properly made and are of the proper kind 

of wire. 


DON’T FORGET THAT YOUR REPUTATION AS AN 
INSPECTOR IS AT STAKE. 










